Thermal extrusions radically reduce the transfer of heat and cold, through the extrusion, by stopping that unwanted energy with a barrier material. Fleetwood uses two methods: Pour/De-bridge and I-Strut. The former process involves pouring polyurethane into an extrusion cavity and removing the underside once the liquid hardens. The I-Strut process involves mechanically joining a polyamide strut to two separate extrusions. Both are proven systems and each offers the Fleetwood Design Team with varying benefits.